Climate change is a disaster that isn't just about poorer countries, by @DavidOAtkins

All nations will suffer the effects of a warmer world, but it is the world's poorest countries that will be hit hardest by food shortages, rising sea levels, cyclones and drought, the World Bank said in a report on climate change.

Under new World Bank President Jim Yong Kim, the global development lender has launched a more aggressive stance to integrate climate change into development.

"We will never end poverty if we don't tackle climate change. It is one of the single biggest challenges to social justice today," Kim told reporters on a conference call on Friday.

The report, called "Turn Down the Heat," highlights the devastating impact of a world hotter by 4 degrees Celsius (7.2 Fahrenheit) by the end of the century, a likely scenario under current policies, according to the report.

"Recent extreme heat waves such as in Russia in 2010 are likely to become the new normal summer in a 4°C world," the authors write. "Tropical South America, central Africa, and all tropical islands in the Pacific are likely to regularly experience heat waves of unprecedented magnitude and duration. In this new high-temperature climate regime, the coolest months are likely to be substantially warmer than the warmest months at the end of the 20th century."

In addition, sea levels will rise by at least 0.5 to 1 meter by century's end, coral reefs and many other marine organisms could go extinct, and many farming areas may have to be abandoned due to higher sea levels and expanding drought.

The report also warns that adaptation efforts may not be enough in world overheated by 4 degrees, especially given the risk of going over climate tipping points.

"There is [...] no certainty that adaptation to a 4°C world is possible," the report says starkly.

"The Earth system's responses to climate change appear to be non-linear," explains, John Schellnhuber, director of the Potsdam Institute for Climate Impact Research (PIK) which co-authored the report for the World Bank along with Climate Analytics. "If we venture far beyond the 2 degrees guardrail, towards the 4 degrees line, the risk of crossing tipping points rises sharply. The only way to avoid this is to break the business-as-usual pattern of production and consumption."

Agricultural yields are expected to decrease for all major cereal crops in all major regions of production. The availability of water will be affected by melting of glaciers, particularly in areas such as the Indus basin and western China, where much of the river flow comes from melt water. Population increases, combined with changes in river run off as a result of changes in rainfall patterns and increased temperatures, could mean that by 2080 significantly less water is available to approximately 1 billion people already living under water stress. For many areas of the world sea level rise, combined with the effect of storms, will threaten low lying coastal communities. There are often very dense populations living along coasts, as well as important infrastructure and high value agricultural land, which makes the impact of coastal flooding particularly severe. The intrusion of salt water on farming land, and the risk to lives of flooding events could affect millions of people worldwide every year.

The impacts are frightening, and the list is not exhaustive. However, the map represents a world where climate change has gone unmitigated, where we have continued to emit greenhouse gases at the rates we are today. If we continue to do this, then the likelihood of the planet warming by 4 degrees Celsius (7 degrees Fahrenheit) increases, and as it does so the risk of these impacts being realised also increases. By taking strong and effective action to curb greenhouse gases emissions, it may be possible to limit this temperature rise to 2 debrees Celsius (4 degrees Fahrenheit). Although this would still bring some adverse impacts, the risk of the very severest impacts, as shown in the Met Office Hadley Centre map, is significantly reduced.